fix b.support_raw_tracepoint for 5.0 kernel
fix b.support_raw_tracepoint for 5.0 kernel

Fix issue #2240.

In 5.0, the following commit
  commit a38d1107f937ca95dcf820161ef44ea683d6a0b1
  Author: Matt Mullins <mmullins@fb.com>
  Date:   Wed Dec 12 16:42:37 2018 -0800

      bpf: support raw tracepoints in modules
renamed the function bpf_find_raw_tracepoint() to
bpf_get_raw_tracepoint(). The bcc relies on checking
bpf_find_raw_tracepoint() in /proc/kallsyms to detect
whether raw_tracepoint is supported in kernel or not.

We do not have better mechanism to detect raw_tracepoint
support without additional syscalls. So tentatively,
let us just check bpf_get_raw_tracepoint() ksym as well
for raw_tracepoint support.

Signed-off-by: Yonghong Song <e76892bbe783db2f627de1232e139db4de43da60@fb.com>

tuxology/bcc,brendangregg/bcc,tuxology/bcc,brendangregg/bcc,tuxology/bcc,iovisor/bcc,tuxology/bcc,iovisor/bcc,brendangregg/bcc,brendangregg/bcc,tuxology/bcc,iovisor/bcc,brendangregg/bcc,iovisor/bcc,iovisor/bcc